We plan to characterize the enzymes present in streptomycetes soil bacteria which phosphorylate members of the streptomycin family of antibiotics with respect to substrate specificities, biological distribution, regulation, and physiological functions. Particular attention will be paid to a stable streptomycin 3"-kinase found in Streptomyces glebosus ATCC 14607 which might represent an ancestral gene for the 3"-kinase present in bacteria clinically resistant to streptomycin. A major effort will be made to characterize the biosynthetic block which occurs in the first mutant found in the biosynthesis of streptomycin. With the use of Demain's mutant it is hoped that additional novel antibiotic analogs can be prepared, in addition to the new antibiotic, streptomutin, already synthesized by Demain with this same mutant.